Wankel rotary engine is simple in configuration, light in weight per output and small in size and generates less vibrations and noise compared to a reciprocating engine. Nevertheless, the Wankel rotary engine is not widely used because a sealing between a triangular rotor eccentrically rotating around a central axis of the cylinder and the cylinder is not complete, a rotation interval at which the rotor absorbs force from combustion gas is short and has lower efficiency than an internal combustion engine and is less durable. As the rotor rotates eccentrically, a contacting angle between the sealing located at a vertex of the triangular rotor and the cylinder continues to change and the airtight sealing is not secured and the sealing effect is sharply reduced by a small wear of the sealing to thereby decrease efficiency.
As another type of a rotary engine different from the Wankel rotary engine, one of the oldest engines is the Hodson's patent rotary engine (Evan 6893) published in Evanion Catalogue of the British Museum. This steam engine (refer to FIG. 4) which is assumed to have been patented in 1884 includes a cylinder, a rotor which rotates using an inner central shaft of the cylinder as an axis, a hinged vane which has one side installed as a hinge in the cylinder and the other side contacting an outer surface of the rotor and reciprocatingly rotates centering on the hinge in accordance with the rotation of the rotor and a steam inducing device to generate the rotational force with respect to the rotor with the force of vapor pressure.
U.S. patent “combustion engine having fuel cut-off at idle speed and compressed air starting and method of operation (U.S. Pat. No. 4,741,164; Date of patent: May 3, 1988) is a rotary engine which is similar in basic shape to the patent engine of Hodson and has a check valve, a compressed air reservoir including an air valve storing excess compressed air and utilizes such compressed air when the engine starts, an air gate, a fuel supply device, and a firing chamber between a compressor module and a combustor module including a cylinder, rotor and an air chamber valve (or firing chamber valve), respectively. The air gate is open by a solenoid operating by a rotation position signal of the rotor and supplies compressed air to the firing chamber and is shut down by a pressure of combustion gas generated by combustion of the firing chamber.
Another U.S. patent rotary engine (U.S. Pat. No. 5,247,916) is similar to the rotary engine according to the present invention in that it includes a compression eccentric as a compressor and a power eccentric as an expander. However, unlike the rotary engine according to the present invention, this rotary engine includes a compression gate and a power gate which have one side fit into a cylinder slot and the other side contacting an outer surface of a rotor by a spring and go inside and come outside the slot when the rotor rotates.
PCT Patent hybrid cycle rotary engine (Patent application No. PCT/US2007/074980) has a compressor module and combustor module but uses a reciprocating rotation valve called rocker instead of a hinged vane. The rocker is closely adhered to the rotor which has one side rotating by an additional cam device or force of a spring.